1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 1991-1998  Linus Torvalds
4  * Re-organised Feb 1998 Russell King
5  * Copyright (C) 2020 Christoph Hellwig
6  */
7 #include <linux/fs.h>
8 #include <linux/major.h>
9 #include <linux/slab.h>
10 #include <linux/ctype.h>
11 #include <linux/vmalloc.h>
12 #include <linux/raid/detect.h>
13 #include "check.h"
14 
15 static int (*check_part[])(struct parsed_partitions *) = {
16 	/*
17 	 * Probe partition formats with tables at disk address 0
18 	 * that also have an ADFS boot block at 0xdc0.
19 	 */
20 #ifdef CONFIG_ACORN_PARTITION_ICS
21 	adfspart_check_ICS,
22 #endif
23 #ifdef CONFIG_ACORN_PARTITION_POWERTEC
24 	adfspart_check_POWERTEC,
25 #endif
26 #ifdef CONFIG_ACORN_PARTITION_EESOX
27 	adfspart_check_EESOX,
28 #endif
29 
30 	/*
31 	 * Now move on to formats that only have partition info at
32 	 * disk address 0xdc0.  Since these may also have stale
33 	 * PC/BIOS partition tables, they need to come before
34 	 * the msdos entry.
35 	 */
36 #ifdef CONFIG_ACORN_PARTITION_CUMANA
37 	adfspart_check_CUMANA,
38 #endif
39 #ifdef CONFIG_ACORN_PARTITION_ADFS
40 	adfspart_check_ADFS,
41 #endif
42 
43 #ifdef CONFIG_CMDLINE_PARTITION
44 	cmdline_partition,
45 #endif
46 #ifdef CONFIG_EFI_PARTITION
47 	efi_partition,		/* this must come before msdos */
48 #endif
49 #ifdef CONFIG_SGI_PARTITION
50 	sgi_partition,
51 #endif
52 #ifdef CONFIG_LDM_PARTITION
53 	ldm_partition,		/* this must come before msdos */
54 #endif
55 #ifdef CONFIG_MSDOS_PARTITION
56 	msdos_partition,
57 #endif
58 #ifdef CONFIG_OSF_PARTITION
59 	osf_partition,
60 #endif
61 #ifdef CONFIG_SUN_PARTITION
62 	sun_partition,
63 #endif
64 #ifdef CONFIG_AMIGA_PARTITION
65 	amiga_partition,
66 #endif
67 #ifdef CONFIG_ATARI_PARTITION
68 	atari_partition,
69 #endif
70 #ifdef CONFIG_MAC_PARTITION
71 	mac_partition,
72 #endif
73 #ifdef CONFIG_ULTRIX_PARTITION
74 	ultrix_partition,
75 #endif
76 #ifdef CONFIG_IBM_PARTITION
77 	ibm_partition,
78 #endif
79 #ifdef CONFIG_KARMA_PARTITION
80 	karma_partition,
81 #endif
82 #ifdef CONFIG_SYSV68_PARTITION
83 	sysv68_partition,
84 #endif
85 	NULL
86 };
87 
bdev_set_nr_sectors(struct block_device * bdev,sector_t sectors)88 static void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors)
89 {
90 	spin_lock(&bdev->bd_size_lock);
91 	i_size_write(bdev->bd_inode, (loff_t)sectors << SECTOR_SHIFT);
92 	bdev->bd_nr_sectors = sectors;
93 	spin_unlock(&bdev->bd_size_lock);
94 }
95 
allocate_partitions(struct gendisk * hd)96 static struct parsed_partitions *allocate_partitions(struct gendisk *hd)
97 {
98 	struct parsed_partitions *state;
99 	int nr = DISK_MAX_PARTS;
100 
101 	state = kzalloc(sizeof(*state), GFP_KERNEL);
102 	if (!state)
103 		return NULL;
104 
105 	state->parts = vzalloc(array_size(nr, sizeof(state->parts[0])));
106 	if (!state->parts) {
107 		kfree(state);
108 		return NULL;
109 	}
110 
111 	state->limit = nr;
112 
113 	return state;
114 }
115 
free_partitions(struct parsed_partitions * state)116 static void free_partitions(struct parsed_partitions *state)
117 {
118 	vfree(state->parts);
119 	kfree(state);
120 }
121 
check_partition(struct gendisk * hd)122 static struct parsed_partitions *check_partition(struct gendisk *hd)
123 {
124 	struct parsed_partitions *state;
125 	int i, res, err;
126 
127 	state = allocate_partitions(hd);
128 	if (!state)
129 		return NULL;
130 	state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
131 	if (!state->pp_buf) {
132 		free_partitions(state);
133 		return NULL;
134 	}
135 	state->pp_buf[0] = '\0';
136 
137 	state->disk = hd;
138 	snprintf(state->name, BDEVNAME_SIZE, "%s", hd->disk_name);
139 	snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
140 	if (isdigit(state->name[strlen(state->name)-1]))
141 		sprintf(state->name, "p");
142 
143 	i = res = err = 0;
144 	while (!res && check_part[i]) {
145 		memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
146 		res = check_part[i++](state);
147 		if (res < 0) {
148 			/*
149 			 * We have hit an I/O error which we don't report now.
150 			 * But record it, and let the others do their job.
151 			 */
152 			err = res;
153 			res = 0;
154 		}
155 
156 	}
157 	if (res > 0) {
158 		printk(KERN_INFO "%s", state->pp_buf);
159 
160 		free_page((unsigned long)state->pp_buf);
161 		return state;
162 	}
163 	if (state->access_beyond_eod)
164 		err = -ENOSPC;
165 	/*
166 	 * The partition is unrecognized. So report I/O errors if there were any
167 	 */
168 	if (err)
169 		res = err;
170 	if (res) {
171 		strlcat(state->pp_buf,
172 			" unable to read partition table\n", PAGE_SIZE);
173 		printk(KERN_INFO "%s", state->pp_buf);
174 	}
175 
176 	free_page((unsigned long)state->pp_buf);
177 	free_partitions(state);
178 	return ERR_PTR(res);
179 }
180 
part_partition_show(struct device * dev,struct device_attribute * attr,char * buf)181 static ssize_t part_partition_show(struct device *dev,
182 				   struct device_attribute *attr, char *buf)
183 {
184 	return sprintf(buf, "%d\n", dev_to_bdev(dev)->bd_partno);
185 }
186 
part_start_show(struct device * dev,struct device_attribute * attr,char * buf)187 static ssize_t part_start_show(struct device *dev,
188 			       struct device_attribute *attr, char *buf)
189 {
190 	return sprintf(buf, "%llu\n", dev_to_bdev(dev)->bd_start_sect);
191 }
192 
part_ro_show(struct device * dev,struct device_attribute * attr,char * buf)193 static ssize_t part_ro_show(struct device *dev,
194 			    struct device_attribute *attr, char *buf)
195 {
196 	return sprintf(buf, "%d\n", bdev_read_only(dev_to_bdev(dev)));
197 }
198 
part_alignment_offset_show(struct device * dev,struct device_attribute * attr,char * buf)199 static ssize_t part_alignment_offset_show(struct device *dev,
200 					  struct device_attribute *attr, char *buf)
201 {
202 	return sprintf(buf, "%u\n", bdev_alignment_offset(dev_to_bdev(dev)));
203 }
204 
part_discard_alignment_show(struct device * dev,struct device_attribute * attr,char * buf)205 static ssize_t part_discard_alignment_show(struct device *dev,
206 					   struct device_attribute *attr, char *buf)
207 {
208 	return sprintf(buf, "%u\n", bdev_discard_alignment(dev_to_bdev(dev)));
209 }
210 
211 static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
212 static DEVICE_ATTR(start, 0444, part_start_show, NULL);
213 static DEVICE_ATTR(size, 0444, part_size_show, NULL);
214 static DEVICE_ATTR(ro, 0444, part_ro_show, NULL);
215 static DEVICE_ATTR(alignment_offset, 0444, part_alignment_offset_show, NULL);
216 static DEVICE_ATTR(discard_alignment, 0444, part_discard_alignment_show, NULL);
217 static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
218 static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
219 #ifdef CONFIG_FAIL_MAKE_REQUEST
220 static struct device_attribute dev_attr_fail =
221 	__ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
222 #endif
223 
224 static struct attribute *part_attrs[] = {
225 	&dev_attr_partition.attr,
226 	&dev_attr_start.attr,
227 	&dev_attr_size.attr,
228 	&dev_attr_ro.attr,
229 	&dev_attr_alignment_offset.attr,
230 	&dev_attr_discard_alignment.attr,
231 	&dev_attr_stat.attr,
232 	&dev_attr_inflight.attr,
233 #ifdef CONFIG_FAIL_MAKE_REQUEST
234 	&dev_attr_fail.attr,
235 #endif
236 	NULL
237 };
238 
239 static struct attribute_group part_attr_group = {
240 	.attrs = part_attrs,
241 };
242 
243 static const struct attribute_group *part_attr_groups[] = {
244 	&part_attr_group,
245 #ifdef CONFIG_BLK_DEV_IO_TRACE
246 	&blk_trace_attr_group,
247 #endif
248 	NULL
249 };
250 
part_release(struct device * dev)251 static void part_release(struct device *dev)
252 {
253 	put_disk(dev_to_bdev(dev)->bd_disk);
254 	iput(dev_to_bdev(dev)->bd_inode);
255 }
256 
part_uevent(struct device * dev,struct kobj_uevent_env * env)257 static int part_uevent(struct device *dev, struct kobj_uevent_env *env)
258 {
259 	struct block_device *part = dev_to_bdev(dev);
260 
261 	add_uevent_var(env, "PARTN=%u", part->bd_partno);
262 	if (part->bd_meta_info && part->bd_meta_info->volname[0])
263 		add_uevent_var(env, "PARTNAME=%s", part->bd_meta_info->volname);
264 	return 0;
265 }
266 
267 struct device_type part_type = {
268 	.name		= "partition",
269 	.groups		= part_attr_groups,
270 	.release	= part_release,
271 	.uevent		= part_uevent,
272 };
273 
delete_partition(struct block_device * part)274 static void delete_partition(struct block_device *part)
275 {
276 	lockdep_assert_held(&part->bd_disk->open_mutex);
277 
278 	fsync_bdev(part);
279 	__invalidate_device(part, true);
280 
281 	xa_erase(&part->bd_disk->part_tbl, part->bd_partno);
282 	kobject_put(part->bd_holder_dir);
283 	device_del(&part->bd_device);
284 
285 	/*
286 	 * Remove the block device from the inode hash, so that it cannot be
287 	 * looked up any more even when openers still hold references.
288 	 */
289 	remove_inode_hash(part->bd_inode);
290 
291 	put_device(&part->bd_device);
292 }
293 
whole_disk_show(struct device * dev,struct device_attribute * attr,char * buf)294 static ssize_t whole_disk_show(struct device *dev,
295 			       struct device_attribute *attr, char *buf)
296 {
297 	return 0;
298 }
299 static DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
300 
301 /*
302  * Must be called either with open_mutex held, before a disk can be opened or
303  * after all disk users are gone.
304  */
add_partition(struct gendisk * disk,int partno,sector_t start,sector_t len,int flags,struct partition_meta_info * info)305 static struct block_device *add_partition(struct gendisk *disk, int partno,
306 				sector_t start, sector_t len, int flags,
307 				struct partition_meta_info *info)
308 {
309 	dev_t devt = MKDEV(0, 0);
310 	struct device *ddev = disk_to_dev(disk);
311 	struct device *pdev;
312 	struct block_device *bdev;
313 	const char *dname;
314 	int err;
315 
316 	lockdep_assert_held(&disk->open_mutex);
317 
318 	if (partno >= DISK_MAX_PARTS)
319 		return ERR_PTR(-EINVAL);
320 
321 	/*
322 	 * Partitions are not supported on zoned block devices that are used as
323 	 * such.
324 	 */
325 	switch (disk->queue->limits.zoned) {
326 	case BLK_ZONED_HM:
327 		pr_warn("%s: partitions not supported on host managed zoned block device\n",
328 			disk->disk_name);
329 		return ERR_PTR(-ENXIO);
330 	case BLK_ZONED_HA:
331 		pr_info("%s: disabling host aware zoned block device support due to partitions\n",
332 			disk->disk_name);
333 		disk_set_zoned(disk, BLK_ZONED_NONE);
334 		break;
335 	case BLK_ZONED_NONE:
336 		break;
337 	}
338 
339 	if (xa_load(&disk->part_tbl, partno))
340 		return ERR_PTR(-EBUSY);
341 
342 	/* ensure we always have a reference to the whole disk */
343 	get_device(disk_to_dev(disk));
344 
345 	err = -ENOMEM;
346 	bdev = bdev_alloc(disk, partno);
347 	if (!bdev)
348 		goto out_put_disk;
349 
350 	bdev->bd_start_sect = start;
351 	bdev_set_nr_sectors(bdev, len);
352 
353 	pdev = &bdev->bd_device;
354 	dname = dev_name(ddev);
355 	if (isdigit(dname[strlen(dname) - 1]))
356 		dev_set_name(pdev, "%sp%d", dname, partno);
357 	else
358 		dev_set_name(pdev, "%s%d", dname, partno);
359 
360 	device_initialize(pdev);
361 	pdev->class = &block_class;
362 	pdev->type = &part_type;
363 	pdev->parent = ddev;
364 
365 	/* in consecutive minor range? */
366 	if (bdev->bd_partno < disk->minors) {
367 		devt = MKDEV(disk->major, disk->first_minor + bdev->bd_partno);
368 	} else {
369 		err = blk_alloc_ext_minor();
370 		if (err < 0)
371 			goto out_put;
372 		devt = MKDEV(BLOCK_EXT_MAJOR, err);
373 	}
374 	pdev->devt = devt;
375 
376 	if (info) {
377 		err = -ENOMEM;
378 		bdev->bd_meta_info = kmemdup(info, sizeof(*info), GFP_KERNEL);
379 		if (!bdev->bd_meta_info)
380 			goto out_put;
381 	}
382 
383 	/* delay uevent until 'holders' subdir is created */
384 	dev_set_uevent_suppress(pdev, 1);
385 	err = device_add(pdev);
386 	if (err)
387 		goto out_put;
388 
389 	err = -ENOMEM;
390 	bdev->bd_holder_dir = kobject_create_and_add("holders", &pdev->kobj);
391 	if (!bdev->bd_holder_dir)
392 		goto out_del;
393 
394 	dev_set_uevent_suppress(pdev, 0);
395 	if (flags & ADDPART_FLAG_WHOLEDISK) {
396 		err = device_create_file(pdev, &dev_attr_whole_disk);
397 		if (err)
398 			goto out_del;
399 	}
400 
401 	/* everything is up and running, commence */
402 	err = xa_insert(&disk->part_tbl, partno, bdev, GFP_KERNEL);
403 	if (err)
404 		goto out_del;
405 	bdev_add(bdev, devt);
406 
407 	/* suppress uevent if the disk suppresses it */
408 	if (!dev_get_uevent_suppress(ddev))
409 		kobject_uevent(&pdev->kobj, KOBJ_ADD);
410 	return bdev;
411 
412 out_del:
413 	kobject_put(bdev->bd_holder_dir);
414 	device_del(pdev);
415 out_put:
416 	put_device(pdev);
417 	return ERR_PTR(err);
418 out_put_disk:
419 	put_disk(disk);
420 	return ERR_PTR(err);
421 }
422 
partition_overlaps(struct gendisk * disk,sector_t start,sector_t length,int skip_partno)423 static bool partition_overlaps(struct gendisk *disk, sector_t start,
424 		sector_t length, int skip_partno)
425 {
426 	struct block_device *part;
427 	bool overlap = false;
428 	unsigned long idx;
429 
430 	rcu_read_lock();
431 	xa_for_each_start(&disk->part_tbl, idx, part, 1) {
432 		if (part->bd_partno != skip_partno &&
433 		    start < part->bd_start_sect + bdev_nr_sectors(part) &&
434 		    start + length > part->bd_start_sect) {
435 			overlap = true;
436 			break;
437 		}
438 	}
439 	rcu_read_unlock();
440 
441 	return overlap;
442 }
443 
bdev_add_partition(struct gendisk * disk,int partno,sector_t start,sector_t length)444 int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
445 		sector_t length)
446 {
447 	struct block_device *part;
448 	int ret;
449 
450 	mutex_lock(&disk->open_mutex);
451 	if (!disk_live(disk)) {
452 		ret = -ENXIO;
453 		goto out;
454 	}
455 
456 	if (partition_overlaps(disk, start, length, -1)) {
457 		ret = -EBUSY;
458 		goto out;
459 	}
460 
461 	part = add_partition(disk, partno, start, length,
462 			ADDPART_FLAG_NONE, NULL);
463 	ret = PTR_ERR_OR_ZERO(part);
464 out:
465 	mutex_unlock(&disk->open_mutex);
466 	return ret;
467 }
468 
bdev_del_partition(struct gendisk * disk,int partno)469 int bdev_del_partition(struct gendisk *disk, int partno)
470 {
471 	struct block_device *part = NULL;
472 	int ret = -ENXIO;
473 
474 	mutex_lock(&disk->open_mutex);
475 	part = xa_load(&disk->part_tbl, partno);
476 	if (!part)
477 		goto out_unlock;
478 
479 	ret = -EBUSY;
480 	if (atomic_read(&part->bd_openers))
481 		goto out_unlock;
482 
483 	delete_partition(part);
484 	ret = 0;
485 out_unlock:
486 	mutex_unlock(&disk->open_mutex);
487 	return ret;
488 }
489 
bdev_resize_partition(struct gendisk * disk,int partno,sector_t start,sector_t length)490 int bdev_resize_partition(struct gendisk *disk, int partno, sector_t start,
491 		sector_t length)
492 {
493 	struct block_device *part = NULL;
494 	int ret = -ENXIO;
495 
496 	mutex_lock(&disk->open_mutex);
497 	part = xa_load(&disk->part_tbl, partno);
498 	if (!part)
499 		goto out_unlock;
500 
501 	ret = -EINVAL;
502 	if (start != part->bd_start_sect)
503 		goto out_unlock;
504 
505 	ret = -EBUSY;
506 	if (partition_overlaps(disk, start, length, partno))
507 		goto out_unlock;
508 
509 	bdev_set_nr_sectors(part, length);
510 
511 	ret = 0;
512 out_unlock:
513 	mutex_unlock(&disk->open_mutex);
514 	return ret;
515 }
516 
disk_unlock_native_capacity(struct gendisk * disk)517 static bool disk_unlock_native_capacity(struct gendisk *disk)
518 {
519 	if (!disk->fops->unlock_native_capacity ||
520 	    test_and_set_bit(GD_NATIVE_CAPACITY, &disk->state)) {
521 		printk(KERN_CONT "truncated\n");
522 		return false;
523 	}
524 
525 	printk(KERN_CONT "enabling native capacity\n");
526 	disk->fops->unlock_native_capacity(disk);
527 	return true;
528 }
529 
blk_drop_partitions(struct gendisk * disk)530 void blk_drop_partitions(struct gendisk *disk)
531 {
532 	struct block_device *part;
533 	unsigned long idx;
534 
535 	lockdep_assert_held(&disk->open_mutex);
536 
537 	xa_for_each_start(&disk->part_tbl, idx, part, 1)
538 		delete_partition(part);
539 }
540 
blk_add_partition(struct gendisk * disk,struct parsed_partitions * state,int p)541 static bool blk_add_partition(struct gendisk *disk,
542 		struct parsed_partitions *state, int p)
543 {
544 	sector_t size = state->parts[p].size;
545 	sector_t from = state->parts[p].from;
546 	struct block_device *part;
547 
548 	if (!size)
549 		return true;
550 
551 	if (from >= get_capacity(disk)) {
552 		printk(KERN_WARNING
553 		       "%s: p%d start %llu is beyond EOD, ",
554 		       disk->disk_name, p, (unsigned long long) from);
555 		if (disk_unlock_native_capacity(disk))
556 			return false;
557 		return true;
558 	}
559 
560 	if (from + size > get_capacity(disk)) {
561 		printk(KERN_WARNING
562 		       "%s: p%d size %llu extends beyond EOD, ",
563 		       disk->disk_name, p, (unsigned long long) size);
564 
565 		if (disk_unlock_native_capacity(disk))
566 			return false;
567 
568 		/*
569 		 * We can not ignore partitions of broken tables created by for
570 		 * example camera firmware, but we limit them to the end of the
571 		 * disk to avoid creating invalid block devices.
572 		 */
573 		size = get_capacity(disk) - from;
574 	}
575 
576 	part = add_partition(disk, p, from, size, state->parts[p].flags,
577 			     &state->parts[p].info);
578 	if (IS_ERR(part) && PTR_ERR(part) != -ENXIO) {
579 		printk(KERN_ERR " %s: p%d could not be added: %ld\n",
580 		       disk->disk_name, p, -PTR_ERR(part));
581 		return true;
582 	}
583 
584 	if (IS_BUILTIN(CONFIG_BLK_DEV_MD) &&
585 	    (state->parts[p].flags & ADDPART_FLAG_RAID))
586 		md_autodetect_dev(part->bd_dev);
587 
588 	return true;
589 }
590 
blk_add_partitions(struct gendisk * disk)591 static int blk_add_partitions(struct gendisk *disk)
592 {
593 	struct parsed_partitions *state;
594 	int ret = -EAGAIN, p;
595 
596 	if (disk->flags & GENHD_FL_NO_PART)
597 		return 0;
598 
599 	if (test_bit(GD_SUPPRESS_PART_SCAN, &disk->state))
600 		return 0;
601 
602 	state = check_partition(disk);
603 	if (!state)
604 		return 0;
605 	if (IS_ERR(state)) {
606 		/*
607 		 * I/O error reading the partition table.  If we tried to read
608 		 * beyond EOD, retry after unlocking the native capacity.
609 		 */
610 		if (PTR_ERR(state) == -ENOSPC) {
611 			printk(KERN_WARNING "%s: partition table beyond EOD, ",
612 			       disk->disk_name);
613 			if (disk_unlock_native_capacity(disk))
614 				return -EAGAIN;
615 		}
616 		return -EIO;
617 	}
618 
619 	/*
620 	 * Partitions are not supported on host managed zoned block devices.
621 	 */
622 	if (disk->queue->limits.zoned == BLK_ZONED_HM) {
623 		pr_warn("%s: ignoring partition table on host managed zoned block device\n",
624 			disk->disk_name);
625 		ret = 0;
626 		goto out_free_state;
627 	}
628 
629 	/*
630 	 * If we read beyond EOD, try unlocking native capacity even if the
631 	 * partition table was successfully read as we could be missing some
632 	 * partitions.
633 	 */
634 	if (state->access_beyond_eod) {
635 		printk(KERN_WARNING
636 		       "%s: partition table partially beyond EOD, ",
637 		       disk->disk_name);
638 		if (disk_unlock_native_capacity(disk))
639 			goto out_free_state;
640 	}
641 
642 	/* tell userspace that the media / partition table may have changed */
643 	kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
644 
645 	for (p = 1; p < state->limit; p++)
646 		if (!blk_add_partition(disk, state, p))
647 			goto out_free_state;
648 
649 	ret = 0;
650 out_free_state:
651 	free_partitions(state);
652 	return ret;
653 }
654 
bdev_disk_changed(struct gendisk * disk,bool invalidate)655 int bdev_disk_changed(struct gendisk *disk, bool invalidate)
656 {
657 	int ret = 0;
658 
659 	lockdep_assert_held(&disk->open_mutex);
660 
661 	if (!disk_live(disk))
662 		return -ENXIO;
663 
664 rescan:
665 	if (disk->open_partitions)
666 		return -EBUSY;
667 	sync_blockdev(disk->part0);
668 	invalidate_bdev(disk->part0);
669 	blk_drop_partitions(disk);
670 
671 	clear_bit(GD_NEED_PART_SCAN, &disk->state);
672 
673 	/*
674 	 * Historically we only set the capacity to zero for devices that
675 	 * support partitions (independ of actually having partitions created).
676 	 * Doing that is rather inconsistent, but changing it broke legacy
677 	 * udisks polling for legacy ide-cdrom devices.  Use the crude check
678 	 * below to get the sane behavior for most device while not breaking
679 	 * userspace for this particular setup.
680 	 */
681 	if (invalidate) {
682 		if (!(disk->flags & GENHD_FL_NO_PART) ||
683 		    !(disk->flags & GENHD_FL_REMOVABLE))
684 			set_capacity(disk, 0);
685 	}
686 
687 	if (get_capacity(disk)) {
688 		ret = blk_add_partitions(disk);
689 		if (ret == -EAGAIN)
690 			goto rescan;
691 	} else if (invalidate) {
692 		/*
693 		 * Tell userspace that the media / partition table may have
694 		 * changed.
695 		 */
696 		kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
697 	}
698 
699 	return ret;
700 }
701 /*
702  * Only exported for loop and dasd for historic reasons.  Don't use in new
703  * code!
704  */
705 EXPORT_SYMBOL_GPL(bdev_disk_changed);
706 
read_part_sector(struct parsed_partitions * state,sector_t n,Sector * p)707 void *read_part_sector(struct parsed_partitions *state, sector_t n, Sector *p)
708 {
709 	struct address_space *mapping = state->disk->part0->bd_inode->i_mapping;
710 	struct folio *folio;
711 
712 	if (n >= get_capacity(state->disk)) {
713 		state->access_beyond_eod = true;
714 		goto out;
715 	}
716 
717 	folio = read_mapping_folio(mapping, n >> PAGE_SECTORS_SHIFT, NULL);
718 	if (IS_ERR(folio))
719 		goto out;
720 
721 	p->v = folio;
722 	return folio_address(folio) + offset_in_folio(folio, n * SECTOR_SIZE);
723 out:
724 	p->v = NULL;
725 	return NULL;
726 }
727